ku-55933 and Fanconi-Anemia

Agents that induce DNA damage can cure some cancers. However, the side effects of chemotherapy are severe because of the indiscriminate action of DNA-damaging agents on both healthy and cancerous cells. DNA repair pathway inhibition provides a less toxic and targeted alternative to chemotherapy. A compelling DNA repair target is the Fanconi anemia (FA) E3 ligase core complex due to its critical-and likely singular-role in the efficient removal of specific DNA lesions. FA pathway inactivation has been demonstrated to specifically kill some types of cancer cells without the addition of exogenous DNA damage, including cells that lack BRCA1, BRCA2, ATM, or functionally related genes. In this perspective, we discuss the genetic and biochemical evidence in support of the FA core complex as a compelling drug target for cancer therapy. In particular, we discuss the genetic, biochemical, and structural data that could rapidly advance our capacity to identify and implement the use of FA core complex inhibitors in the clinic.

Topics: Ataxia Telangiectasia Mutated Proteins; BRCA1 Protein; BRCA2 Protein; DNA Damage; DNA Repair; Enzyme Inhibitors; Fanconi Anemia; Fanconi Anemia Complementation Group Proteins; Gene Expression Regulation, Neoplastic; Humans; Molecular Targeted Therapy; Morpholines; Pyrones; RNA, Small Interfering; Signal Transduction; Synthetic Lethal Mutations; Ubiquitin-Protein Ligases; Ubiquitins

The clonogenic assay examines cell sensitivity to toxic agents and has been shown to correlate with normal tissue sensitivity to radiotherapy in cancer patients. The clonogenic assay is not clinically applicable due to its intra-individual variability and the time frame of the protocol. We aimed to develop a clinically applicable assay that correlated with the clonogenic assay.. We have developed a faster and less labor-intensive cell division assay (CD assay) using flow cytometry and incorporation of a fluorescent thymidine analogue. The CD assay was calibrated to the clonogenic assay and optimized for peripheral blood lymphocytes.. Following ionizing radiation of primary human skin fibroblasts, the four-day CD assay gave similar results as the 14-day clonogenic survival assay. In lymphocytes isolated from patient blood samples, the CD assay was able to detect increased radiosensitivity in ataxia telangiectasia patients and increased radiosensitivity after in vitro treatment with DNA-PK and ATM inhibitors. The CD assay found a variation in the intrinsic radiosensitivity of lymphocytes isolated from healthy control samples. The CD assay was able to measure the anti-proliferation effect of different chemotherapeutic drugs in lymphocytes.. Our results indicate that the CD assay is a fast and reliable method to measure the anti-proliferation effect of DNA-damaging agents with a potential to find the most sensitive patients in the work-up before cancer treatment.

Topics: Ataxia Telangiectasia; Ataxia Telangiectasia Mutated Proteins; Cell Proliferation; Cells, Cultured; Chromones; Clinical Laboratory Techniques; Colony-Forming Units Assay; DNA Damage; DNA-Activated Protein Kinase; Fanconi Anemia; Fibroblasts; Flow Cytometry; Humans; Lymphocytes; Morpholines; Pyrones; Radiation Tolerance; Radiation, Ionizing; Skin